JP2000195078A - Objective lens drive - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] To provide an objective lens driving device capable of correcting not only a focusing direction, a tracking direction, and a radial direction twist of a movable portion on a disk but also a tangential direction twist. . SOLUTION: The objective lens driving device 100 includes a movable unit 1
The movable unit 150 includes a base 50 for supporting the objective lens 50, the objective lens 1 for recording and reproducing optical information on a disk-shaped recording medium, the lens holder 2 for holding the objective lens 50, At least four permanent magnets 3a fixed to
3d, the supporting means includes four substantially parallel metal wires 4 having one end fixed to the holder 2 and the other end connected to the base 9, and the metal wires 4 connected to the base 9 An elastic support member 10 having a connection to each other end.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an objective lens driving device for an apparatus for optically recording or reproducing information on a disk-shaped recording medium.

[0002]

2. Description of the Related Art An objective lens driving device moves an objective lens in a direction perpendicular to a disk with respect to a focusing deviation due to a vertical movement of a warp of a disc-shaped recording medium (hereinafter referred to as a disk) such as a compact disk or a tracking deviation due to eccentricity. (Hereinafter referred to as a focusing direction) and a disk radial direction (hereinafter referred to as a tracking direction).

In the optical information recording / reproducing apparatus including the objective lens driving apparatus as described above, focusing control,
If a tilt of the optical axis of the objective lens with respect to the disk surface (hereinafter referred to as tilt) occurs in addition to the tracking control, an optical aberration occurs, which causes deterioration of a signal at the time of recording and reproduction.

In order to solve such a problem, in a conventional optical recording / reproducing apparatus, at least one permanent magnet is fixed to a movable body, as disclosed in Japanese Patent Application Laid-Open No. 9-22537. There has been proposed a device that performs tilt correction by adjusting currents flowing through at least two focusing coils fixed to a base.

Hereinafter, a conventional objective lens driving device will be described with reference to the drawings. FIG. 11 is a perspective view showing a configuration of a conventional objective lens driving device 500, and FIG. 12 is an explanatory diagram showing definitions of symbols.

In FIG. 11, reference numeral 101 denotes an objective lens,
02 is a lens holder for holding the objective lens 101, 10
3a and 103b are permanent magnets fixed to the lens holder 102, 104 is a suspension wire, 105a to 105a
05d is an opposing yoke, 106a to 106d are tracking coils, 107a to 107d are focusing coils, 108 is a suspension holder, and 109 is a fixed base. The movable section 550 includes the objective lens 101, the lens holder 102, and the permanent magnets 103a and 103b. One end of the suspension wire 104 is a movable part 5
The other end is fixed to the suspension holder 108.
It is stuck to.

Here, FIG. 12 shows the definition of the moving direction of the movable portion 550. In FIG. 12, Fo is parallel to the optical axis in the focusing direction, and Tr is orthogonal to the Fo direction in the tracking direction. Rt is a radial tilt, which is an inclination around an axis in the tangential tilt direction. T
t is a tangential tilt, which is an inclination around an axis in the tracking direction.

The operation of the conventional objective lens driving device 500 will be described below with reference to FIG. When the movable part 550 is driven in the tracking direction Tr, the permanent magnet 1
An electromagnetic force is generated which is orthogonal to the magnetic fluxes generated at 03a and 103b and the currents flowing through the tracking coils 106a to 106d. Since the tracking coils 106a to 106d are fixed to the base 109, the movable coils 550 are relatively movable.
Substantially translates in the tracking direction Tr.

On the other hand, the movable part 550 is moved in the focusing direction F.
o, the magnetic fluxes generated by the permanent magnets 103a and 103b and the focusing coils 107a to 107b
By generating an electromagnetic force orthogonal to the current flowing through d, the movable part 550 similarly translates substantially in the focusing direction Fo.

Driving of the movable portion 550 in the radial tilt direction Rt is performed by focusing coils 107a and 107c.
Driving Force in Fo Direction and Focusing Coil 107
The driving force in the Fo direction by b and 107d is applied in the opposite direction, and a moment M is applied to the movable portion 550 around the Y axis.
r. Therefore, tilt correction is enabled by supporting and driving the movable portion 550 as described above.

[0011]

In an optical recording / reproducing apparatus using a disk, in order to improve the recording capacity, it is necessary to use an objective lens having a high aperture ratio to perform recording / reproducing with a smaller diameter condensing spot. is increasing. In this case, the degree of aberration due to the tilt, which is the relative inclination of the optical axis of the objective lens with respect to the disk, increases in proportion to the cube of the aperture ratio. Optical axis tilt correction is required.

However, in the above configuration, it is possible to correct the radial tilt (R tilt) direction due to the warpage of the disk or the like, but it is possible to correct the tangential tilt due to the bending of the disk or the so-called tangent tilt. There has been a problem that it is difficult to correct in the initial tilt (T tilt) direction.

The present invention has been made in view of the above-mentioned problems of such a conventional objective lens driving device. An object of the present invention is to provide a focusing direction with respect to a disk of a movable portion,
It is an object of the present invention to provide an objective lens driving device capable of correcting not only the tracking direction and the radial tilt direction but also the tangential tilt direction.

Another object of the present invention is to provide a spring constant for determining the sensitivity in a low frequency region (primary resonance frequency) in the correction of the tangential tilt direction with a degree of freedom and an object having an optimum driving characteristic. An object of the present invention is to provide a lens driving device.

[0015]

An objective lens driving device according to the present invention includes a movable portion, support means for supporting the movable portion, and a base for holding the support means, wherein the movable portion comprises: An objective lens for recording or reproducing optical information on or from a disc-shaped recording medium, a lens holder for holding the objective lens, and at least four permanent magnets fixed to the lens holder; At least four substantially parallel metal wires, one end of which is fixed to the lens holder and the other end of which is connected to the base, and which is connected to the base and connected to the other end of each of the metal wires. An elastic support member having a connection portion, wherein the base is fixed to the base and is opposed to each of the permanent magnets; and the objective lens is wound around each of the yokes. Wherein the a focusing coil having a winding axis in the optical axis direction, a tracking coil and perpendicular to the focusing coil wound around each of the yokes, the objects can be achieved.

The objective lens driving device further includes a control unit for applying a current to each of the focusing coils, and the control unit drives the lens holder in a focusing direction, a radial tilt direction, and a tangential tilt direction. Then, the direction of the current may be switched.

The elastic supporting member may have a plate-like or rod-like shape, and each of the connecting portions may be elastically deformed such that each of the other ends can be deformed in the longitudinal direction of the metal wire. .

Each of the yokes is disposed to face each of the permanent magnets along a longitudinal direction of the metal wire, and each of the yokes and each of the permanent magnets are pulled by each of the metal wires. A force may be applied and the pulling force may be generated based on a respective resultant magnetic attraction between each of the yokes and each of the permanent magnets.

The distance between each of the yokes and each of the permanent magnets may be set so that a tensile force is applied to each of the metal wires.

[0020] The thickness of each of the metal wires in the longitudinal direction may be set so that a tensile force is applied to each of the metal wires.

The spring force required for each of the connecting portions to elastically deform in the longitudinal direction of the metal wire may be at least larger than the magnetic attraction force.

The lens holder includes a relay member to which the one end of the metal wire is fixed, a lens holder main body for holding the objective lens, and a connection between the lens holder main body and the relay member. An elastically deformable member that deforms the holder body so as to rotate in the tangential tilt direction may be included.

Another objective lens driving device according to the present invention is:
Movable part, supporting means for supporting the movable part, and a base for holding the supporting means, the movable part, an objective lens for recording or reproducing optical information on a disc-shaped recording medium, A lens holder for holding the objective lens,
At least two permanent magnets fixed to the lens holder, wherein the support means includes at least four substantially parallel ones fixed at one end to the lens holder and the other end connected to the base. Including a metal wire, the base has a yoke fixed to the base and arranged to face the permanent magnet, and a winding axis wound around each of the yokes in a direction of an optical axis of the objective lens. A focusing coil, and a tracking coil wound around each of the yokes orthogonal to the focusing coil, wherein the lens holder holds the relay member to which the one end of the metal wire is fixed, and the objective lens The lens holder body and the relay member are connected to each other so that the lens holder body rotates in the tangential tilt direction. And a resiliently deformable member to deform, the objects can be achieved.

The elastically deformable member is torsionally deformed about a rotation axis so that the lens holder body rotates in a tangential tilt direction, and has an L-shaped or cross-shaped cross section perpendicular to the rotation axis. It may include a leaf spring having a shape.

[0025] The elastically deformable member may have a hinge shape.

The elastically deformable member is torsionally deformed about a rotation axis so that the lens holder body is rotated in a tangential tilt direction. May be arranged so as to pass through the center of gravity.

The elastically deformable member is torsionally deformed about a rotation axis so that the lens holder body is rotated in a tangential tilt direction. May be arranged so as to pass through the principal point of

The elastically deformable member includes a leaf spring that is torsionally deformed about a rotation axis so that the lens holder body rotates in a tangential tilt direction. The leaf spring is covered with a damping material. Is also good.

The return force associated with the rotation of the elastically deformable member may be greater than at least the magnetic attraction generated around the rotation axis between each of the yokes and each of the permanent magnets.

[0030]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIGS. 1A and 1B show an objective lens driving apparatus 100 according to Embodiment 1 of the present invention.
FIG. 2 is a schematic diagram showing a radial tilt operation in the first embodiment of the present invention, and FIG. 3 is a schematic diagram showing a tangential tilt operation of the movable portion in the first embodiment of the present invention. is there.

In FIGS. 1 and 1B, reference numeral 1 denotes an objective lens, 2 denotes a lens holder for holding the objective lens 1, and 3a to 3a.
3d are permanent magnets fixed to the lens holder 2, Ha to H
d is the direction of magnetization of the permanent magnets 3a to 3d, 4 is a suspension wire, 5a to 5d are opposed yokes, 6a to 6d are tracking coils, 7a to 7d are focusing coils, 8 is a suspension holder, 9 is a fixed base, 10 Is a tilt spring, Tr is a tracking direction, Fo is a focusing direction, Rt is a radial tilt direction, Tt is a tangential tilt direction, ± Fa to ± Fd (decoding in the same order) are current directions of the focusing coils 7a to 7b, ± Ta to
± Td (decoding order) is the current direction of the tracking coils 6a to 6b. However, the negative sign of the current is not shown.
FIG. 12 shows the definitions of the Tr direction to the Tt direction.

The objective lens 1 and the permanent magnets 3a to 3d are fixed to the lens holder 2 to form a movable section 150. One end of the suspension wire 4 is a movable part 15
0 and the other end is fixed to a tilt spring 10, and the tilt spring 10 is fixed to a fixed base 9 via a suspension holder 8. The movable portion 150 includes a tracking coil 6a-6d and a focusing coil 7 wound around magnetic fields of the permanent magnets 3a-3d fixed to itself and yokes 5a-5d fixed to the fixed base 9.
It is driven by an electromagnetic force generated by a current supplied to a to 7d.

Next, the movement and driving of the movable section 150 will be described with reference to FIGS. 1 and 1B. As shown in FIGS. 1 and 1B, the movable portion 150 is supported by four suspension wires 4 so as to be capable of translational movement in the direction of the symbol Fo and Tr in the figure. In addition,
Each direction and its symbol are defined in FIG.

The driving force for the movable portion 150 in the + Fo direction is obtained when the directions of the currents flowing through the focusing coils 7a to 7d are + Fa, + Fb, + Fc, and + Fd, respectively, and the movable portion 150 translates in the + Fo direction. . The driving force for the movable unit 150 in the + Tr direction is obtained when the directions of the currents flowing through the tracking coils 6a to 6d are + Ta, + Tb, + Tc, and + Td, respectively, and the movable unit 150 translates in the + Tr direction.

Next, referring to FIG. 2A to FIG.
Driving and supporting in the radial tilt Rt direction of 0 will be described. 2A to 2D, FIG.
0, a partial perspective view of the suspension wire 4 and the tilt spring 10, and FIGS. 2B to 2D are front views of the movable section 150 as viewed from the direction of the arrow VR in FIG. 2A.

In FIG. 2A to FIG. 2D, the symbol Y
, The symbol r is the distance between the Y axis and the center of the suspension wire 4, and ± Mr is the Y acting on the movable part 150.
The moment force around the axis, 4 'is the position after the suspension wire 4 is driven in the radial tilt Rt direction, ±
Foa to ± Fod are driving forces acting on the movable unit 150.

In FIG. 2A, the driving forces -Foa, -Fo
c, + Fob, + Fod are respectively -Fa, -Fc, + F for the focusing coils 7a to 7d in FIG. 1B.
b, obtained by passing a current in the + Fd direction. The driving force −Foa, −Foc, + Fob, + F shown in FIG. 2A
The radial tilt Rt operation when Fod acts on the movable unit 150 will be described with reference to FIGS. 2B to 2D. 2B shows a state where no driving force is applied to the movable section 150 (initial state), and FIGS. 2C and 2D show a radial tilt Rt state.

As shown in FIG. 2C, the aforementioned driving force-Fo
a, -Foc, + Fob, + Fod
0 acts as a moment force about the Y axis + Mr. Due to the moment force + Mr, the suspension wire 4 is deformed such that the trajectory of the end on the movable portion 150 side is twisted along the circumference of the radius r.

FIG. 2D shows a driving state of the movable unit 150 when a moment force -Mr acts in the opposite direction to the case of FIG. 2C. The moment force -Mr has the opposite sign to that of FIG. 2C. Focusing coils 7a to 7d
Obtained by flowing through.

As described above, the movable portion 150 is driven to the radial tilt Rt by the current directions of the four focusing coils 7a to 7d, and is supported so as to be displaceable in that direction by the twist of the suspension wire 4.

Next, referring to FIG. 3A to FIG.
Driving and supporting in the tangential tilt Tt direction of 0 will be described. FIG. 3A is a partial perspective view of the movable portion 150, the suspension wire 4, and the tilt spring 10, and FIG.
3D shows the movable portion 150 viewed from the direction of the arrow Vt in FIG. 3A.
FIG.

3A to 3D, reference numeral 10a denotes a deformation center axis of the tilt spring 10, symbol X denotes an axis defined in FIG.
Mt is a moment force acting on the movable portion 150 around the axis in the tangential tilt direction, and ± Foa to ± Fod are driving forces acting on the movable portion 150.

In FIG. 3A, driving force + Foa, -Fo
c, + Fob, and -Fod are + Fa, -Fc, and + F, respectively, for the focusing coils 7a to 7d in FIG. 1B.
b, obtained by applying a current in the -Fd direction. The driving force + Foa, -Foc, + Fob,-shown in FIG. 3A.
The tangential tilt Tt operation when Fod acts on the movable unit 150 will be described with reference to FIGS. 3B to 3D.

FIG. 3B shows a state in which no driving force acts on the movable portion 150 (initial state), and FIGS. 3C and 3D show a tangential tilt Tt state. As shown in FIG. 3C, the above-described driving forces + Foa, -Foc, + Fob, -F
The resultant force of od acts on the movable portion 150 as a moment force around the X axis + Mt. The suspension wire 4 receives the buckling force in the tension / compression direction by the moment force + Mt. As shown in FIGS. 3C and 3D, the buckling force causes the tilt spring 10 to deform around its deformation center axis 10a.

That is, due to the deformation of the tilt spring 10, the fixed-side support portion 4A of the suspension wire 4 is displaced in the tension and compression directions, respectively. Therefore, the movable section 150 is supported so as to be movable in the tangential tilt direction Tt in proportion to the displacement of the fixed-side support section 4A.

As described above, according to the first embodiment, four driving means and suspension wires 4 are provided.
By providing the tilt spring 10 that supports the fixed-side support portion 4A of the movable portion 15A so as to be displaceable in the tension and compression directions, the movable portion 15
0 is the focusing direction Fo, the tracking direction Tr,
Driving and supporting in four axial directions of the radial tilt direction Rt and the tangential tilt direction Tt can be easily realized.

The same operation and effect can be obtained even if the tilt spring 10 is replaced by a rod-shaped elastic support member, and the fixed-side support portion 4A of the suspension wire 4 can be displaced in the tension / compression direction by bending or twisting the support member. can get.

The same operation and effect can be obtained by changing the shape of the fixed support portion 4A of the suspension wire 4 and forming the rod-shaped elastic support member and the suspension wire 4 into an integrated structure. Further, when the rod-shaped elastic support member and the suspension wire 4 are formed as an integrated structure, a further effect that the tilt spring 10 becomes unnecessary can be obtained.

FIGS. 4A to 4C show the current directions of the focusing coils 7a to 7d and the focusing coil 7a.
FIG. 7 is a schematic diagram showing a connection between 7d and a focusing coil drive circuit 11; 4A to 4C, focusing coil drive circuit 11 controls the direction and magnitude of current for focusing coils 7a to 7d, respectively.

FIG. 4A shows the focusing coils 7a to 7d when the movable part 150 is driven in the focusing direction Fo.
The direction of the current flowing through 7d is shown. FIG. 4B shows the movable unit 15.
This shows the direction of the current flowing through the focusing coils 7a to 7d when 0 is driven in the radial tilt direction Rt. FIG. 4C shows the movable unit 150 in the tangential tilt direction T.
5 shows the direction of the current flowing through the focusing coils 7a to 7d when driving to t.

Although the focusing coils 7a to 7d and the focusing coil drive circuit 11 are connected as shown in FIGS. 4A to 4C, when the movable section 150 is driven in the focusing direction Fo, the focusing coils 7a to 7d are used. , A current flows as if they were connected as shown in FIG. 5A.

When the movable section 150 is driven in the radial tilt direction Rt, a current flows through the focusing coils 7a to 7d as if they were connected as shown in FIG. 5B. A current flows in the focusing coils 7a and 7c in a direction opposite to the direction of the current flowing through the focusing coils 7b and 7d.

When driving the movable part 150 in the tangential tilt direction Tt, the focusing coils 7a to
A current flows through 7d as if it were connected as shown in FIG. 5C. A current flows in the focusing coils 7a and 7b in a direction opposite to the direction of the current flowing through the focusing coils 7c and 7d.

The focusing coil 7a is controlled based on the focus error signal and the tracking error signal.
By changing the magnitude of the drive current flowing through to 7d, good control characteristics can be obtained.

(Embodiment 2) FIG. 6A is a schematic diagram showing a configuration of an objective lens driving device 200 according to Embodiment 2 of the present invention. In FIG. 6A, Ga to Gd are the respective gaps between the permanent magnets 3a to 3d and the opposing yokes 5a to 5d, Da to Dd are the thicknesses of the opposing yokes 5a to 5d in the magnetic field direction, and the symbols ± Mf are the permanent magnets 3a to 3d. And opposing yoke 5
Tw is a magnetic force acting on the movable portion 150 due to the magnetic attraction force between the points a to 5, and Tw is a tension acting on the suspension wire 4 due to the magnetic attraction force described above.

In FIG. 6A, Ga <Gc and Gb <
The permanent magnets 3a to 3d and the opposing yoke 5a are set to Gd.
-5d are set. Since the magnetic attraction force is inversely proportional to the gaps Ga to Gd, a magnetic force acts on the movable portion 150 in the + Mf direction, and a tension in the Tw direction is always applied to the suspension wire 4.

As described above, according to the second embodiment, deformation such as buckling of the suspension wire 4 is avoided, and stable support of the movable portion can be always realized.

It is to be noted that the thicknesses Da to Gd in FIG.
It is also possible to set a relationship of Da> Dc and Db> Dd with respect to Dd. Since the magnetic attraction force is proportional to the yoke thickness, a magnetic force acts on the movable portion 150 in the + Mf direction, and a tension in the Tw direction is always applied to the suspension wire 4. Therefore, instead of the difference between the gaps Ga to Gd, the thicknesses Da to Dd in FIG.
When the relationship of> Dc and Db> Dd is set, the same operation and effect as the above-described operation and effect can be obtained.

(Embodiment 3) FIG. 6B is a schematic diagram showing a configuration of an objective lens driving device 300 according to Embodiment 3 of the present invention. In FIG. 6B, Ua to Ud are suspension wires 4 acting on each bent portion of the tilt spring 10.
Is a reaction force to each tension Tw.

According to the present invention, each spring force Ua of the tilt spring
Ud is Ua> Tw, Ub> Tw, Uc> T, respectively.
w, Ud> Tw. Further, each spring force Ua to Ud of the tilt spring is set smaller than the spring force of the suspension wire 4 in the buckling direction.

As described above, according to the third embodiment, the positioning accuracy of the movable portion is maintained with respect to the Tw direction tension for stabilizing the support of the movable portion shown in the second embodiment. At the same time, the effect of the buckling resonance of the suspension wire on the movable part can be reduced.

(Embodiment 4) FIG. 7 is a perspective view of an objective lens driving device 400 according to Embodiment 4 of the present invention, FIG. 8 is an exploded perspective view defining a driving direction, and FIGS. 9A and 9B are tangential. It is a rotation model figure by the rotation axis position of drive. Since the present invention relates to the configuration of the tangential drive, the model in the fourth embodiment will be described using an example of an objective lens drive device that performs three-axis drive of focusing drive, tracking drive, and tangential drive. However, the invention is not so limited. The present invention can be applied to the objective lens driving device that performs the four-axis driving described in the first embodiment.

7 and 8, reference numeral 1 denotes an objective lens, 2 denotes a lens holder, 3a and 3b denote permanent magnets, 4a to
4d is a suspension wire, 5a and 5b are opposing yokes, 6a and 6b are tracking coils, 7a and 7b are focusing coils, 8 is a suspension holder, 9 is a fixed base, 10a and 10b are elastically deformable members, 11
a and 11b are relay members, 12 is a disk, and O is the center of gravity of the rotating part.

Referring to FIG. 8, the definition of the driving direction of movable section 450 is the same as the definition described above with reference to FIG. In contrast, ± Tt is a tangential tilt direction indicating a tilt operation in a circumferential direction with respect to the disk recording surface.

The objective lens 1 and the permanent magnets 3a and 3b are fixed to the lens holder 2, and the relay members 11a and 11b are connected to the lens holder 2 via the elastically deformable members 10a and 10b. Is composed. One end of each of the suspension wires 4a to 4d is fixed to the suspension holder 8 installed on the fixed base 9,
The other end is fixed to the relay members 11a and 11b,
The whole 50 is supported so as to be displaceable in the focusing direction and the tracking direction. Further, tracking coils 6a, 6b and focusing coils 7a, 7b are wound around the opposed yokes 5a, 5b, and the permanent magnets 3a, 3b
And is fixed to the fixed base 9.

The elastically deformable members 10a and 10b connect the lens holder 2 and the relay members 11a and 11b to which the suspension wires 4a to 4d are fixed, respectively.
Are rotatably supported around the axes of the elastically deformable members 10a and 10b, that is, in the tangential tilt direction ± Tt. The extension of the rotation axis of the elastically deformable members 10a and 10b passes through the center of gravity O of the rotation part including the objective lens 1 and the lens holder 2 (FIG. 8).

Next, driving and control will be described.
In the focusing drive, the electromagnetic force that the permanent magnets 3a and 3b receive with respect to the electromagnetic magnetic flux generated by the coil is + Fo, + F
The focusing coils 7a,
Focusing drive is performed by supplying a current to each of the electrodes 7b. Similarly, in the tracking drive, the electromagnetic force that the permanent magnets 3a and 3b receive with respect to the electromagnetic magnetic flux generated by the coil is + T.
A tracking drive is performed by supplying currents to the tracking coils 6a and 6b so as to be in the same direction of r and + Tr. In the focusing control and the tracking control, the error signal is always minimized with reference to a signal from an optical error detecting means (not shown) for detecting a deviation of the light beam due to disk fluctuation such as disk surface deviation or eccentricity. And control by following.

In the tangential drive, the permanent magnets 3a,
An electric current is applied to the focusing coils 7a and 7b so that the electromagnetic force 3b receives the electromagnetic forces + Fo and -Fo (or -Fo and + Fo) in opposite directions to generate a rotational moment in the ± Tt direction in the movable portion to generate a tangential tilt direction. To work. The rotating shaft at this time is an elastically deformable member 10a,
It is a rotation shaft of 10b. The tangential tilt control is performed so that the tilt is always minimized with reference to an error signal from a tilt detecting means (not shown) such as a tilt sensor, or the time axis error signal (jitter) is always an optimum value. The tangential drive is performed to remove the influence of the optical aberration due to the tilt of the objective lens 2 to realize stable recording and reproduction.

Next, details and effects of the elastically deformable members 10a and 10b will be described. Elastically deformable member 1
Numerals 0a and 10b denote torsionally deformable leaf springs mainly made of a spring material such as phosphor bronze. The elastically deformable member 10 shown in FIG.
The cross sections of a and 10b have a cross shape. This is to provide sufficient rigidity for the parallel movement in the direction perpendicular to the axis while supporting the rotation part to be sufficiently soft in the rotation direction of the rotation part, and to suppress the occurrence of unnecessary displacement. This is to realize stable operation.

The spring constant of the elastically deformable members 10a and 10b in the rotating direction can be arbitrarily set by changing the axial length, plate thickness, and shape. Therefore, an optimum drive sensitivity can be obtained in a low frequency region of the tangential tilt drive characteristic.

In fixing the suspension wires 4a to 4d, the suspension wires 4a and 4b (not shown)
, 4c and 4d are arranged substantially in parallel with each other in the focusing direction, and are fixed to rigid relay members 11a and 11b and the suspension holder 8 at both ends of each combination. As a result, the entire movable portion 450 moves in the focusing direction, and the suspension wire 4
Even if a through d are curved, the movable portions 4 move while the virtual planes perpendicular to the axes at both ends of the suspension wires 4 a through 4 d are held substantially in parallel.
The posture of 50 is maintained almost constant, and stable driving is obtained.

The return force of the elastically deformable members 10a, 10b around the rotation axis is applied to the permanent magnets 3a, 3b of the movable part.
And the torsion plate spring constant is set so as to be larger than the magnetic attraction force around the rotation axis of the elastically deformable members 10a and 10b generated between the opposed yokes 5a and 5b fixed to the fixed base 9. Thus, the movable section 450 can maintain a constant posture even under the influence of the magnetic attraction, and can realize stable driving.

When the elastically deformable members 10a and 10b are covered with a damping material such as silicon, the amplitude value of the tangential drive characteristic at the primary resonance frequency can be reduced.

As shown in FIG. 9A, the extension of the rotation axis of the elastically deformable members 10a and 10b passes through the center of gravity O of the rotation part including the objective lens 1 and the lens holder 2, so that the dynamic balance is maintained. Stable tangential drive is obtained.

On the other hand, as shown in FIG. 9B, when the extension of the rotation axis of the elastically deformable members 10a and 10b is set to a position passing through the principal point O 'of the objective lens 1, the rotation part is centered on O'. Therefore, the translation amount of the objective lens 1, that is, the movement in the disk circumferential direction is suppressed, and the effect of minimizing the time axis fluctuation of the recording / reproducing signal can be obtained.

As shown in FIG. 10, the elastically deformable members 10a and 10b are
A similar effect can be obtained by a configuration in which the movable portion 450 is supported so as to rotate in the ± Tt direction using the a and 13b. The spring return force in the rotation axis direction by the hinge is set to an optimum value by adjusting the material of the hinge member and the shape and thickness of the hinge portion.
If the hinge member is further configured as an integral part with the relay members 11a and 11b, the number of parts is reduced and the cost can be reduced.

In the fourth embodiment, for simplicity of description, the objective lens driving device for performing three-axis driving of focusing driving, tracking driving, and tangential driving has been described as a model. , 3
b. The focusing coils 7a and 7b can be divided into two parts in the tracking drive axis direction, and can be used as a four-axis drive objective lens drive device that also enables radial tilt drive.

[0079]

As described above, according to the present invention, the movable means is provided by providing the four driving means in the focusing direction and the tilt spring for supporting the fixed side support of the suspension wire in the tension and compression directions. Driving and supporting the unit in four axial directions of focusing, tracking, radial tilt, and tangential tilt can be easily realized.

According to the present invention, the magnetic attraction force of the permanent magnet fixed to the movable portion and the opposing yoke fixed to the fixed base acts in the tension direction of the suspension wire. Deformation is avoided, and stable support of the movable portion can be always achieved.

Further, according to the present invention, the spring force of the tilt spring is set to be sufficiently larger than the tension force of the suspension wire and smaller than the spring force in the buckling direction, so that the positioning accuracy of the movable portion is maintained. At the same time, the effect of the buckling resonance of the suspension wire on the movable part can be reduced.

Further, according to the present invention, the relay member to which the other end of the suspension wire is fixed and the lens holder are connected by an elastically deformable member, and the rotating portion including the lens holder is supported so as to be rotatable. Accordingly, it is possible to set an arbitrary primary resonance frequency of tangential driving and an appropriate driving sensitivity.

Further, according to the present invention, even when the movable part moves in the focusing direction, the translational movement of the suspension wire in the axial direction does not occur, so that the posture of the movable part is maintained and stable tangential driving can be realized.

[Brief description of the drawings]

FIG. 1A is a perspective view showing a configuration of an objective lens driving device according to a first embodiment of the present invention.

FIG. 1B is a perspective view showing a configuration of an objective lens driving device according to Embodiment 1 of the present invention.

FIG. 2A is a schematic diagram showing a radial tilt operation according to the first embodiment of the present invention.

FIG. 2B is a front view showing a radial tilt operation according to the first embodiment of the present invention.

FIG. 2C is a front view showing the radial tilt operation in the + Rt direction according to the first embodiment of the present invention.

FIG. 2D is a front view showing the radial tilt operation in the −Rt direction according to the first embodiment of the present invention.

FIG. 3A is a schematic diagram showing a tangential tilt operation in Embodiment 1 of the present invention.

FIG. 3B is a front view showing a tangential tilt operation in the first embodiment of the present invention.

FIG. 3C is a front view showing a tangential tilt operation in the + Tt direction according to the first embodiment of the present invention.

FIG. 3D is a front view showing the tangential tilt operation in the −Tt direction according to the first embodiment of the present invention.

FIG. 4A is a focusing direction F according to a fourth embodiment.
FIG. 4 is a schematic diagram showing connection of a focusing coil and a current direction in driving to o.

FIG. 4B is a diagram illustrating a radial tilt direction R according to the fourth embodiment.
The schematic diagram which shows the connection of a focusing coil, and the electric current direction in drive to t.

FIG. 4C is a schematic diagram showing connection of a focusing coil and a current direction in driving in a tangential tilt direction Tt according to the fourth embodiment.

FIG. 5A is a focusing direction F according to a fourth embodiment.
FIG. 4 is a schematic diagram showing a current direction of a focusing coil in driving to o.

FIG. 5B is a diagram illustrating a radial tilt direction R according to the fourth embodiment.
The schematic diagram which shows the electric current direction of the focusing coil in the drive to t.

FIG. 5C is a schematic diagram showing a current direction of a focusing coil in driving in a tangential tilt direction Tt according to the fourth embodiment.

FIG. 6A is a schematic diagram illustrating a configuration of an objective lens driving device according to a second embodiment of the present invention.

FIG. 6B is a schematic diagram showing a configuration of an objective lens driving device according to Embodiment 3 of the present invention.

FIG. 7 is a perspective view showing a configuration of an objective lens driving device according to a fourth embodiment of the present invention.

FIG. 8 is an exploded perspective view showing a definition of a driving direction according to a fourth embodiment of the present invention.

FIG. 9A is a model diagram of rotation by a rotation axis position of tangential drive according to Embodiment 4 of the present invention.

FIG. 9B is a model diagram of rotation by a rotation axis position of tangential drive according to Embodiment 4 of the present invention.

FIG. 10 is a schematic diagram of an objective lens driving device using a hinge as an elastically deformable member according to a fourth embodiment of the present invention.

FIG. 11 is a perspective view showing a configuration of a conventional objective lens driving device.

FIG. 12 is an explanatory diagram showing definitions of symbols.

[Explanation of symbols]

1,101 Objective lens 2,102 Lens holder 3a-3d, 103a-103b Permanent magnet 4,104 Suspension wire 5a-5d, 105a-105d Opposed yoke 6a-6d, 106a-106d Tracking coil 7a-7d, 107a-107d Focusing Coil 8,108 Suspension holder 9,109 Fixed base 10 Tilt spring Tr Tracking direction Fo Focusing direction Rt Radial tilt direction Tt Tangential tilt direction Mr Moment force Mt Moment force Ga-Gd Gap Da-Dd Opposed yoke thickness Tw tension Ua- Ud reaction force

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kanji Wakabayashi 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor Jin Fujii 1006 Kadoma Kadoma Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Hiroshi Yamamoto 1006 Kadoma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. (72) Inventor Teruyuki Takizawa 1006 Odaka Kadoma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd.

Claims (15)

[Claims] 1. A movable part, a supporting means for supporting the movable part, and a base for holding the supporting means, wherein the movable part is for recording or reproducing optical information on a disk-shaped recording medium. An objective lens, a lens holder holding the objective lens, and at least four permanent magnets fixed to the lens holder, wherein the support means has one end fixed to the lens holder and the other end fixed to the base. At least four metal wires substantially parallel to each other connected to a base, and an elastic support member having a connection portion connected to the base and connected to the other end of each of the metal wires, A base fixed to the base and opposed to each of the permanent magnets; a focusing core wound around each of the yokes and having a winding axis in the optical axis direction of the objective lens. And a tracking coil wound around each of the yokes orthogonal to the focusing coil. 2. The objective lens driving device further includes a control unit that applies a current to each of the focusing coils, wherein the control unit drives the lens holder in a focusing direction, a radial tilt direction, and a tangential tilt direction. Switch the direction of the current so that
The objective lens driving device according to claim 1. 3. The elastic support member has a plate-like or rod-like shape, and each of the connecting portions is elastically deformed such that each of the other ends is deformable in a longitudinal direction of the metal wire. The objective lens driving device according to claim 1. 4. Each of the yokes is disposed to face each of the permanent magnets along a longitudinal direction of the metal wire, and each of the yokes and each of the permanent magnets are:
The metal wire is arranged so that a tensile force is applied to each of the metal wires, wherein the tensile force is generated based on a resultant force of magnetic attraction forces between each of the yokes and each of the permanent magnets. Item 2. The objective lens driving device according to Item 1. 5. The objective lens driving device according to claim 4, wherein a distance between each of said yokes and each of said permanent magnets is set such that a tensile force is applied to each of said metal wires. 6. The objective lens driving device according to claim 4, wherein a longitudinal thickness of each of said metal wires of said yoke is set such that a tensile force is applied to each of said metal wires. 7. The objective lens driving device according to claim 4, wherein a spring force required for each of said connecting portions to elastically deform in a longitudinal direction of said metal wire is larger than at least said magnetic attraction force. 8. The lens holder, wherein: a relay member to which the one end of the metal wire is fixed; a lens holder body holding the objective lens; and a connection between the lens holder body and the relay member;
The objective lens driving device according to claim 1, further comprising: an elastically deformable member that deforms the lens holder body so as to rotate in a tangential tilt direction. 9. A movable part, a support means for supporting the movable part, and a base for holding the support means, wherein the movable part is for recording or reproducing optical information on a disk-shaped recording medium. An objective lens, a lens holder for holding the objective lens, and at least two permanent magnets fixed to the lens holder, wherein the support means has one end fixed to the lens holder and the other end fixed to the base. At least four metal wires substantially parallel to each other connected to a base, wherein the base is fixed to the base and is disposed opposite to the permanent magnet, and is wound around each of the yokes. A focusing coil that is turned and has a winding axis in the optical axis direction of the objective lens, and a tracking coil wound around each of the yokes orthogonal to the focusing coil, The lens holder, a relay member to which the one end of the metal wire is fixed, a lens holder main body that holds the objective lens, and a connection between the lens holder main body and the relay member,
An objective lens driving device comprising: an elastically deformable member that deforms the lens holder main body to rotate in a tangential tilt direction. 10. The elastically deformable member is torsionally deformed about a rotation axis so that the lens holder body rotates in a tangential tilt direction, and a cross section perpendicular to the rotation axis has an L-shape or a tenth shape. The objective lens driving device according to claim 9, further comprising a leaf spring having a V-shape. 11. The objective lens driving device according to claim 9, wherein the elastically deformable member has a hinge shape. 12. The elastically deformable member is torsionally deformed about a rotation axis so that the lens holder main body is rotated in a tangential tilt direction. The objective lens driving device according to claim 9, wherein the objective lens driving device is disposed so as to pass through the center of gravity of the movable portion. 13. The elastically deformable member is torsionally deformed around a rotation axis so that the lens holder main body is rotated in a tangential tilt direction. The objective lens driving device according to claim 9, wherein the objective lens driving device is disposed so as to pass through a principal point of the objective lens. 14. The elastically deformable member includes a leaf spring that is torsionally deformed about a rotation axis so that the lens holder body rotates in a tangential tilt direction, and the leaf spring is covered with a damping material. The objective lens driving device according to claim 9, wherein the driving is performed. 15. The return force accompanying the rotation of the elastically deformable member is at least larger than a magnetic attraction force generated between each of the yokes and each of the permanent magnets around the rotation axis. 10. The objective lens driving device according to 9.